Earthquakes

Materials:

1. Plastic Table
    
2. Three cups of sand
    
3. Rubber Mallet

1. The students will pour three cups of sand on the top of a plastic table near the edge.
   They will tap the table lightly with the rubber mallet. When they tap the table lightly they will see the sand "jump" into the air.
   The teacher should explain that as rocks snap and break at the focus of an earthquake shock waves are sent out in all directions. The "jumping sand" represents the release of the energy from the hammer through the plastic table.
    
2. The students should move the sand farther away from the point of contact and see what happens.
   The farther away the sand is from the source of energy (tapping of rubber mallet) the less the sand jumps. This represents the fact that the farther you are from
   the epicentre the less you will feel the earthquakes shock waves.
    
3. The students should move the sand to the opposite side of the table and tap lightly. They should observe a very small movement of the sand.
   
    
4. Shear Waves
   
   Materials: Skipping Rope
   Two students will hold the ends of the jump rope and raise their hands up and down shaking the jump rope and producing S waves. The waves in the jump rope will have an up and down motion.

   
   The teacher will explain that the S waves of an earthquake look like the waves produced by the shaking of the skipping rope. These are secondary waves.
   
   Compression Waves
   
   Materials:

   1. Slinky

   
   Two students will hold the Slinky at the two ends pulling and stretching it slightly. One student will push the Slinky, slowly watching the Compression wave as it rolls from one end of the Slinky to the other. The teacher will explain that the waves produced with the Slinky are like Compression or Primary waves of an earthquake.